A night at the Bronze does nothing to improve the Slayer's morale, as Willow notices when she sees Buffy reject a guy. Willow tries to help her friend out, but Buffy opts to stop by the school and see if Giles has any work for her to do. Unbeknownst to her, a boy is fighting with a girl in the school hallway. He holds up a gun, and the girl tries to leave the scene. The boy then shouts, "Don't walk away from me, bitch!" Buffy arrives at the school just in time to stop the boy from shooting the girl. Buffy knocks the gun out of his hand, and the boy soon returns to his senses. While he and the girl try to figure out what just happened, the school janitor points out that the gun is nowhere to be seen.

The next morning, Principal Snyder calls Buffy to his office to let her know that he'll be keeping an eye on her. After he leaves the office for a minute, a book mysteriously falls out of the bookshelf. Buffy picks it up, noticing that it's a yearbook from the Sunnydale Class of '55. Meanwhile, Giles stops by the computer classroom, where Willow is still serving as the substitute teacher. She tells Giles about some of the files and pagan websites she found on the computer, then gives him a rose quartz that once belonged to Jenny. Elsewhere, Buffy has a dream in one of her classes that she's in the year 1955. She watches on as one of the students approaches the teacher. They start to hold hands when someone else interrupts them. Just then, Buffy wakes up from her dream and notices the teacher writing "Don't walk away from me, bitch" on the chalkboard. He doesn't even notice it until the students start laughing. In the hallway, Buffy tells Xander what happened. When they reach his locker, a rotted arm reaches out of it and grabs Xander, trying to pull him in. Buffy helps him loose, and the creature disappears. When Giles finds out about this, he deduces that this is some form of paranormal activity.

Later that night, one of the teachers, Ms. Frank, passes by George the janitor on her way home. Suddenly, they begin to reenact the same conversation that the boy and girl held the night before. While this goes on, Giles is working in his office when he hears a female voice call to him. He believes that it is Jenny's voice. When he walks out to investigate, he sees George and Ms. Frank outside. Before Giles can do anything, the gun goes off, sending Ms. Frank over the edge and onto the steps below. George tries to flee the scene, but Giles tackles him. After the gun is knocked out of George's hands, it suddenly vanishes into thin air. George has no idea what just happened, so Giles fills him in.

The next day, Giles tells the others that he believes the ghost is Jenny. They don't see how the pieces fit, but Giles remains set in his belief. In the computer classroom, Willow looks up any previous shooting victims in the school. She finds a record from 1955, when a student shot his teacher, then himself. Buffy recognizes the faces from her dream, so she grabs a 1955 yearbook and looks them up. The boy was James Stanley, and his teacher was Grace Newman. Buffy determines that they were having an affair. However, Buffy feels no remorse for James's fate, for she feels he deserved whatever punishment there was after shooting Grace. In the cafeteria, Cordy complains about the upcoming Sadie Hawkins dance when another paranormal event occurs. This time, all of the food transforms into snakes, sending the entire school population into panic. One of the snake bites Cordy's cheek before she swats it away. After they evacuate the school, a team is sent in to clean out the snakes. Principal Snyder talks with his friend on the police force, Bob. Snyder knows that they're on a Hellmouth, but Bob demands Snyder to control the situation, otherwise the mayor would have to get involved. That night, Willow sets up a plan to exorcise the spirit from the school. To do so, Buffy, Xander, Cordelia, and herself need to chant from different locations in the school at midnight, forming what is called a Mangus Tripod. Buffy elects to take the center position, since that is where the most danger would likely occur. After they split up in the school, Willow runs into Giles by the library. He is trying to contact Jenny's spirit, so Willow leaves him alone. As midnight approaches, Buffy sees a vision of James dancing with Grace in the band room. Cordelia inspects her wound in the bathroom mirror, then watches in horror as the whole side of her face turns red and swollen. Willow is suddenly pulled into the floor by an arm, but she is saved by Giles. Buffy watches as James's face is replaced by a rotted skull, which tells her to get out. The clock finally strikes twelve, so the group does the chant simultaneously. However, it doen't work like it's supposed to. A swarm of wasps invades the hallways, and everybody makes a mad dash for the exit. They run to the street, then turn around to witness the swarm surround the entire school.

At Buffy's house, Giles deduces that it is James spirit which is haunting Sunnydale High. He is apparently trying to seek forgiveness from Grace, but that can never happen since she dies before she can possibly forgive him. So, he is doomed to repeat this scenario over and over again. While they try to figure out a solution, Buffy hears a male voice call to her. Without telling the others, she sneaks off to the school. The wasps part to allow her access, and she walks right in. Inside, Buffy meets Angel, who has come to finish things off. However, James spirit possesses Buffy, and she begins to act out the scenario. Confused for a moment, Angel approaches and is suddenly possessed by Grace's spirit. It all plays out the same way, only this time, Grace (in Angel's body) gets up after being shot and falling onto the steps below. In the band room, James (in Buffy's body) prepares to shoot himself, when Grace stops him. She forgives him, and they share one last kiss before their souls finally cross over, leaving Buffy and Angel in an embrace, kissing like they once did in the past. When Angel realizes what he is doing, he pushes her off and escapes.

Back at the Summers home, Buffy realizes that James never meant to shoot Grace. Apparently, Buffy and James had more in common than she realized, for they were both tormented by guilt. Meanwhile, at their new home in an abandoned garden, Angel tries to cleanse himself from the vile kiss he shared with his enemy. He takes Dru out with him to find some blood, leaving Spike alone. After they leave, Spike rises from his wheelchair and kicks it on its side, knowing that the time for his comeback is nearer than anyone else thinks.